* [PATCH RESEND v3] Trivial comment fix for the CRC ITU-T polynom
@ 2021-08-31 13:07 Roger Knecht
2021-08-31 14:15 ` Randy Dunlap
0 siblings, 1 reply; 3+ messages in thread
From: Roger Knecht @ 2021-08-31 13:07 UTC (permalink / raw)
To: Jiri Kosina, Dan Carpenter
Cc: Jiri Kosina, Jonathan Corbet, linux-doc, kernel-janitors,
linux-kernel, Roger Knecht
This patch fixes a small typo in the CRC ITU-T polynom documentation.
The code comment says that the polynom is x^16 + x^12 + x^15 + 1, but the
correct polynom is x^16 + x^12 + x^5 + 1.
Quote from page 2 in the ITU-T V.41 specification:
"2 Encoding and checking process
The service bits and information bits, taken in conjunction, correspond
to the coefficients of a message polynomial having terms from x^(n-1)
(n = total number of bits in a block or sequence) down to x^16. This
polynomial is divided, modulo 2, by the generating polynomial
x^16 + x^12 + x^5 + 1. [...]"
Source: https://www.itu.int/rec/T-REC-V.41-198811-I/en
The hex polynom 0x1021 and CRC code implementation are correct.
Signed-off-by: Roger Knecht <roger@norberthealth.com>
---
Changes for the resend:
- Moved "changes and thanks" out of the commit message.
Thanks,
Roger
include/linux/crc-itu-t.h | 2 +-
lib/crc-itu-t.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/crc-itu-t.h b/include/linux/crc-itu-t.h
index a4367051e192..2f991a427ade 100644
--- a/include/linux/crc-itu-t.h
+++ b/include/linux/crc-itu-t.h
@@ -4,7 +4,7 @@
*
* Implements the standard CRC ITU-T V.41:
* Width 16
- * Poly 0x1021 (x^16 + x^12 + x^15 + 1)
+ * Poly 0x1021 (x^16 + x^12 + x^5 + 1)
* Init 0
*/
diff --git a/lib/crc-itu-t.c b/lib/crc-itu-t.c
index 1974b355c148..56e6e0d63d1e 100644
--- a/lib/crc-itu-t.c
+++ b/lib/crc-itu-t.c
@@ -7,7 +7,7 @@
#include <linux/module.h>
#include <linux/crc-itu-t.h>
-/** CRC table for the CRC ITU-T V.41 0x1021 (x^16 + x^12 + x^15 + 1) */
+/** CRC table for the CRC ITU-T V.41 0x1021 (x^16 + x^12 + x^5 + 1) */
const u16 crc_itu_t_table[256] = {
0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH RESEND v3] Trivial comment fix for the CRC ITU-T polynom
2021-08-31 13:07 [PATCH RESEND v3] Trivial comment fix for the CRC ITU-T polynom Roger Knecht
@ 2021-08-31 14:15 ` Randy Dunlap
2021-08-31 15:06 ` Roger Knecht
0 siblings, 1 reply; 3+ messages in thread
From: Randy Dunlap @ 2021-08-31 14:15 UTC (permalink / raw)
To: Roger Knecht, Jiri Kosina, Dan Carpenter
Cc: Jiri Kosina, Jonathan Corbet, linux-doc, kernel-janitors, linux-kernel
On 8/31/21 6:07 AM, Roger Knecht wrote:
> This patch fixes a small typo in the CRC ITU-T polynom documentation.
>
> The code comment says that the polynom is x^16 + x^12 + x^15 + 1, but the
> correct polynom is x^16 + x^12 + x^5 + 1.
>
> Quote from page 2 in the ITU-T V.41 specification:
> "2 Encoding and checking process
>
> The service bits and information bits, taken in conjunction, correspond
> to the coefficients of a message polynomial having terms from x^(n-1)
> (n = total number of bits in a block or sequence) down to x^16. This
> polynomial is divided, modulo 2, by the generating polynomial
> x^16 + x^12 + x^5 + 1. [...]"
>
> Source: https://www.itu.int/rec/T-REC-V.41-198811-I/en
>
> The hex polynom 0x1021 and CRC code implementation are correct.
>
> Signed-off-by: Roger Knecht <roger@norberthealth.com>
> ---
> Changes for the resend:
> - Moved "changes and thanks" out of the commit message.
>
> Thanks,
> Roger
>
> include/linux/crc-itu-t.h | 2 +-
> lib/crc-itu-t.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/crc-itu-t.h b/include/linux/crc-itu-t.h
> index a4367051e192..2f991a427ade 100644
> --- a/include/linux/crc-itu-t.h
> +++ b/include/linux/crc-itu-t.h
> @@ -4,7 +4,7 @@
> *
> * Implements the standard CRC ITU-T V.41:
> * Width 16
> - * Poly 0x1021 (x^16 + x^12 + x^15 + 1)
> + * Poly 0x1021 (x^16 + x^12 + x^5 + 1)
> * Init 0
> */
>
> diff --git a/lib/crc-itu-t.c b/lib/crc-itu-t.c
> index 1974b355c148..56e6e0d63d1e 100644
> --- a/lib/crc-itu-t.c
> +++ b/lib/crc-itu-t.c
> @@ -7,7 +7,7 @@
> #include <linux/module.h>
> #include <linux/crc-itu-t.h>
>
> -/** CRC table for the CRC ITU-T V.41 0x1021 (x^16 + x^12 + x^15 + 1) */
> +/** CRC table for the CRC ITU-T V.41 0x1021 (x^16 + x^12 + x^5 + 1) */
> const u16 crc_itu_t_table[256] = {
> 0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
> 0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
I should have noticed this earlier:
Please change the /** to a simple /*.
/** means "beginning of kernel-doc comment" and this is not
a kernel-doc comment.
Thanks.
--
~Randy
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH RESEND v3] Trivial comment fix for the CRC ITU-T polynom
2021-08-31 14:15 ` Randy Dunlap
@ 2021-08-31 15:06 ` Roger Knecht
0 siblings, 0 replies; 3+ messages in thread
From: Roger Knecht @ 2021-08-31 15:06 UTC (permalink / raw)
To: Randy Dunlap
Cc: Jiri Kosina, Dan Carpenter, Jiri Kosina, Jonathan Corbet,
linux-doc, kernel-janitors, linux-kernel
Hi Randy,
No problem, I will update the patch.
Regards,
Roger
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-08-31 13:07 [PATCH RESEND v3] Trivial comment fix for the CRC ITU-T polynom Roger Knecht
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